Drilling machines are used in various applications, such as the drilling of quarries, tunnels or mines. These machines are composed of a carrier part, called carrier, on which there is a slide rail, said slide rail receiving a hydraulic drilling apparatus.
A hydraulic drilling apparatus includes, in a known manner:                a casing comprising a front part,        a shank intended to be coupled to at least one drill rod equipped with a tool, such as a drilling bit, the shank including a fluid injection conduit capable of injecting a fluid, such as water or air in the at least one drill rod so as to extract from the boreholes the destroyed pieces of rock,        a striking piston slidably mounted inside the casing along a striking axis and configured to strike the shank,        an extraction piston slidably mounted inside the front part of the casing and disposed around the shank, the extraction piston comprising an extraction portion configured to cooperate with the shank, and        a cartridge removably mounted on the front part and disposed around the shank, the cartridge including an injection part intended to be connected to a fluid delivery conduit, the injection part being configured to fluidly connect the fluid injection conduit to the fluid delivery conduit.        
Such a hydraulic drilling apparatus allows easily removing the tool from the rock after the completion of the borehole, including when the drilled ground is unstable or faulted. Indeed, when the tool is blocked in the borehole, an operator displaces the casing of the hydraulic drilling apparatus away from the tool until the extraction portion of the extraction piston bears against the shank which is secured to the tool through the drill rod(s), and actuates hydraulic circuits for controlling the striking piston such that said striking piston strikes the shank. A shock wave is therefore transmitted to the extraction piston which is projected forwards in the direction of a recoil chamber containing an elastic oil cushion capable of exerting a thrust force on the extraction piston biasing said extraction piston backwards causing an impact against the shank ensuring a release of the tool out of the borehole.
A drawback of such a hydraulic drilling apparatus lies in the fact that a replacement of the shank, which is a wear part whose regular replacement is necessary (approximately every 30 to 50 hours), requires a disassembly of the front part of the casing which integrates the extraction piston and the associated hydraulic circuits and which is held by a plurality of tie rods (generally between 2 and 4 tie rods). This front part of the casing is very heavy, and its disassembly requires a specific tooling. Furthermore, during the intervention time, oil flows from the hydraulic circuits associated with the extraction piston, which results in oil loss and soil pollution.